对分查找算法（迭代和递归方式）

二分查找法是对一组有序的数字中进行查找，传递相应的数据，进行比较查找到与原数据相同的数据，查找到了返回对应的数组下标，失败返回-1。

迭代方式

public static int binarysearch(int[] srcArray, int des){
	int low = 0;
	int high = srcArray.length-1;
	while(low <= high){
		int middle = (low + high)/2; 
		if(des == srcArray[middle]){
			return middle; 
		}else if(des <srcArray[middle]){
			high = middle - 1; 
		}else { 
			low = middle + 1; 
		}
	} 
	return -1; 
}

递归方式

public static int binarySearch(int[] arr,int first,int last,int des){
	int mid=(first+last)/2;
	if(first>last)
		return -1;
	else if(des==arr[mid])
		return mid;
	else if(des<arr[mid])
		return binarySearch(arr, first, mid-1, des);
	else
		return binarySearch(arr, mid+1, last, des);
}

测试代码

public static void main(String[] args){
	System.out.println(binarysearch(src, 32)); 
	System.out.println(binarySearch(src,0,src.length-1,48)); 
}